<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <div id="111" mjw="222">这是一个块</div>
</body>
<script src="jquery-3.6.3.js"></script>
<script>
    console.log( $("div").attr("mjw"));
    console.log( $("div").prop("mjw"));

    $("div").attr("mjw","333")
    
    $("div").prop("mjw","444")

    console.log( $("div")).prop("id")
    $("div").prop("id","prop1")
</script>
</html>